A Computational Model of Hippocampus: A Unified Theory About Engram and Sharp-Ware Ripples

The hippocampus is key to memory encoding, consolidation, and retrieval. Previous work shows that neurons in the hippocampus fire in sequence to encode spatial information. The same group of cells will replay in memory consolidation, coupled with ripples, spindle, and slow waves. As for episodic memory, engram cells have been proposed to explain the encoding and transformation of episodic memory. Another universe theory about memory is the cognitive map theory. Here I use cognitive map theory as the bridge to overcome the gap between spatial and episodic memory. I believe spatial memory is a highly compressed case of episodic memory. In addition, I propose the hypothesis that engram can trigger sharp-wave ripples. I use a spike neural network-based computational model to verify this hypothesis. In conclusion, I believe engram cells and sharp-wave ripples are two different phenomena under a unified memory system.